The Nigeria-based Boko Haram, a jihadist organization that pledged allegiance to the Islamic State of Iraq and Syria (ISIS/ISIL) earlier this year, has been named the world’s deadliest terrorist group in a new study.

Boko Haram, which continues to wage jihad against authorities in and around Nigeria, was responsible for more deaths than any other terrorist group in the world in 2014.

The study revealed that Boko Haram was responsible for 6,664 deaths last year, compared to 6,073 by ISIS, which Newsweek notes, “Continues to spread its bloodthirsty brand of extremism in Europe, Africa and the Middle East.”

Boko Haram’s executions in 2014 surged by more than 300 percent when compared to those in 2013, the study said, noting that the killings last year included numerous suicide bombings and murders in dozens of villages and towns.

By late October, a portion of the al-Shabaab had pledged allegiance to ISIS, showing a further fracture within the Somalia-based jihadist group.

“On Tuesday, Boko Haram was suspected of responsibility in an explosion that killed more than 30 people in the northeastern city of Yola,” reports Newsweek. “A day later, two female suicide bombers, one thought to be 11-years-old, killed at least 15 people at a busy mobile phone market in the northern city of Kano.”

The Global Terrorism Index 2015 revealed that militant attacks worldwide are currently at their highest level ever—nine times more than in 2000.

In 2014, deaths from terrorist attacks increased by 80 percent to 32,658. Most of the attacks (78 percent) occurred in only five countries: Pakistan, Nigeria, Afghanistan, Syria, and Iraq.

ISIS and Boko Haram were responsible for more than half (51 percent) of the terrorism-linked deaths in 2014.

“Boko Haram has waged an insurgency in Nigeria since 2009 in its bid to create a mini-state under Islamic law,” notes Newsweek:

It has forced at least 2.6 million people from their homes, killing at least 17,000 people and abducting hundreds, including the 276 schoolgirls kidnapped in Chibok village in April last year that prompted an international outcry. As of April, a year after their kidnap, 219 of the Chibok schoolgirls remained missing. A group of around 50 managed to escape.

Nigerian President Muhammadu Buhari urged the nation on Wednesday to remain vigilant, conceding that even his recently intensified military offensive against Boko Haram could not stop every attack.

“President Buhari reassures Nigerians that his administration is very much determined to wipe out Boko Haram in Nigeria and bring all perpetrators of these heinous crimes against humanity to justice,” said a statement from the Nigerian president’s office.